26 PATTEN AND REDENBAUGH. 



EXPLANATION OF PLATE IL 



Fig. 5. X 45. Endosternite of Apus, neural side, anterior extremity towards 

 top of plate. The jagged ends (m.) furnish attachment for the muscles of the 

 mandibles. The anterior cornua (a. r.) are each divided into three parts (h., m., 

 and «.). A pair of chitinous apodemes {apo.) project into the endosternite on 

 the posterior side. Muscles going to the maxillae are attached to the small 

 processes at x. A few strands going to the integument are attached at y. The 

 process 2; is a thin membrane attached to the integument between the longitudi- 

 nal commissures of the ventral cord. 



Fig. 6. X 45. Endosternite of Apus, haemal side. Longitudinal abdominal 

 muscles are attached to the jagged processes {w.) on the posterior side. Other 

 reference letters as in Fig. 5. 



Fig. 7. X 60. Sagittal section of endosternite of Ap7is near median line; 

 anterior end towards the right of figure. It shows the neighboring integument 

 {int.) with the muscles going to it from y, the relations of the membrane z to the 

 integument, and the positions of the cross-commissures {cr. com}-^) with reference 

 to the endosternite. 



Fig. 8. X 60. A section of the plastron of Apus a little farther from the 

 median line than the preceding. It shows the apodeme (apo^ and the tendinous 

 cord running from it, through the plastron, to the anterior cornu (a. c). The 

 process x, the membrane z, and the projections due to attachment of abdominal 

 muscles to posterior side of apodeme are cut by this section. 



Fig. 9. X 60. A section of the plastron of Apus still farther from the median 

 line. The apodeme {apo!) is approaching the exterior. All three divisions {h., tn., 

 and n.) of the anterior cornu {a. c.) are cut through. 



Fig. 10. X 60. A cross-section through posterior part of plastron of Apus. 

 It cuts the inner ends of the apodemes {apo.), the muscles at y, and a pair of 

 ganglia of the ventral cord {v. c). 



Fig. II. X 10. Endosternite of Mygale, neural side. The anterior cornua 

 {a. ^.) are very large. The neural processes {n.pr.) are in contact with the integu- 

 ment. The neural plates (w./.'-^) project vertically from the body of the plastron. 

 The ends of the five haemal processes {h.pr}-^) protrude beyond the edges of the 

 plastron. The posterior process {p- pr) is not cleft, as in Limubis. 



Fig. 12. X 10. Endosternite of Mygale, haemal side. Five pairs of haemal 

 processes {h. pr.^~^) rise from the sides of the hollow in which the intestine lies. 

 Reference letters as in Fig. 11. 



